The present invention relates generally to networks that have dynamically changing, bandwidth limited links, for example, wireless networks of mobile nodes, and more particularly, to methods that provide network management for these networks resulting in improved quality of service (QoS).
Methods to provide QoS for wireless ad hoc networks are being developed at many telecommunications technology companies, at universities, and by the Mobile Ad Hoc Network (MANET) Internet Engineering Working Group. A representative sample of this work is disclosed by S. Chakrabarti and A. Mishra in a paper entitled “QoS Issues in Ad Hoc Wireless Networks”, IEEE Communications Magazine, pp. 142-148, February, 2001, which provides an overview of the academic work in this area. This document states at page 148 that: “We have not even mentioned the issue of network management for ad hoc networks with QoS in the main text; to our knowledge neither has anyone else.”
When a user's data flow is interrupted by a fault, which might be due to a link failure or to contention in a node-to-node link that the flow is using, the interruption persists until the network control means establishes a new route that circumvents the fault. The time required to re-route the flow, referred to as the network time constant, is characteristic of the network control means and may depend on the size of the network.
The methods of the prior art incur delays while they detect faults and then discover or select alternate routes. The prior art discovery processes generate demand for bandwidth that can further degrade performance. This causes real-time flows to be interrupted. When these interruptions are lengthy or occur frequently, the performance may be unacceptable for applications like real-time voice communications or video teleconferencing. Moreover, the prior art does not recognize user precedence, leading to unpredictable and erratic connectivity when the network resource usage approaches saturation.
It is therefore an objective of the present invention to provide for methods or algorithms that provide improved quality of service (QoS) for dynamic networks by providing more predictable performance. It is also an objective of the present invention to provide for methods or algorithms that do not add burden onto resources that are already heavily utilized.